Abstract 5898: Gut microbiota-derived metabolism of 5-fluorouracil affects drug efficacy

Abstract

Abstract Introduction: Fluoropyrimidines are drugs currently used as a first-line treatment for colorectal cancer (CRC)1. The impact of gut bacteria on 5-Fluorouracil (5FU) activity remains relatively unknown. The objective of this analysis was to delineate potential bacteria-drug interactions that modify 5FU. Methods: Tumor and tumor-adjacent healthy tissue samples from 130 colorectal adenocarcinoma patients, 55% males and 45% females, median age of 71 years old (36-91 age range), were extracted following surgical resection of the tumor. TNM classification varied across the cohort (15% pT1, 43% pT2, 35% pT3, 4% pT4). 16s rRNA gene amplicon sequencing was performed to map the microbiome composition of tumor and paired normal mucosa. 20 bacterial from the genera whose abundance changed significantly between tumor and healthy tissue were incubated with 5FU to assess drug-bacteria interactions. Ultra-performance liquid chromatography-mass spectrometry (UPLC-MS) was employed to identify changes in drug concentration (Wilcoxon spare rank test) as well as products of bacteria-driven drug metabolism. A metabolic activity-based assay was used to assess viability of a colorectal adenocarcinoma cell line (HCA46) following co-incubation with microbe-driven drug metabolites, aiming to determine significant effects on 5FU efficacy, assessed by 2-way ANOVA. Results: Escherichia coli BW25113, Bifidobacterium longum, Citrobacter freundii and Enterococcus faecalis significantly modify 5FU in vitro, allowing us to conclude that bacteria can metabolise the drug (q < 0.001). Ruminococcus gnavus does not have the ability to metabolise the drug as no significant change in 5FU concentration was observed. Incubation of microbe-derived drug metabolites with HCA46 resulted in significant decrease in cell viability compared to incubation with 5FU only, indicating that bacteria-5FU interactions result in increase of drug efficacy (Figure 2). Conclusion: This is the first report of 5FU metabolism by Escherichia coli BW25113, Bifidobacterium longum, Citrobacter freundii and Enterococcus faecalis in vitro. This study provides an insight into the potential of large and small intestinal bacteria in chemically modifying chemotherapeutic agents and therefore modulating their activity. 1. Mahipal A, Grothey A. Role of biologics in first-line treatment of colorectal cancer. J Oncol Pract. 2016. Citation Format: Despoina Chrysostomou, Mark David, James L. Alexander, Julian R. Marchesi, James M. Kinross. Gut microbiota-derived metabolism of 5-fluorouracil affects drug efficacy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 5898.